What is the consensus for the track? Planning to get in on the latest apex group buy. Have been leaning towards a staggered 9.5/10.5 setup with 265/285 tires, but really have minimal data to go by. From what I gather, the max tire a square setup will allow is 275 (on a 18x10 wheel, someone correct me if I am wrong). While it has the advantages of being able to rotate tires and save some money in the long run, does it affect the "feel" or inherent balance of the car on track? My only experience at this point with the 1M on the track is with the stock 245/265 ps2s, which I find to be quite good.

If someone could outline the respective advantages/disadvantages of each setup, I would be very appreciative. Thanks in advance.

I am running the stagered size that you are "leaning" too with 275 on the rear. I am running NT05's and you get a little rubbing on the fronts in thigher corners and under compression but not bad and after you wear some tread away (2-3 session depending on how hard you run) it goes away. I am happy with the setup but I am planning to drop to 18's and square set up when i wear out my current set of tires. Unfortunately they only have 1 event on them so I'll have to wait awhile. My reason to going square is the same one's you listed in addition to the fact that 18" r-comps are much cheaper and readily available than 19's.

A square set up will significantly reduce understeer on an otherwise stock car and greatly attributes to a more neutral handling car. The ability to rotate and work the car through the corner also becomes much easier when you have the same amount of grip in the front as the rear, in a square set up. Almost all BMW owners at track days and club races end up using square wheel and tire set ups (unless they have very high power levels) because of the control and ability to manipulate the car in certain ways are much higher when there is greater front end grip. It really comes down to everyone's different preferences with their own car and their driving styles.

A square set up will significantly reduce understeer on an otherwise stock car and greatly attributes to a more neutral handling car. The ability to rotate and work the car through the corner also becomes much easier when you have the same amount of grip in the front as the rear, in a square set up. Almost all BMW owners at track days and club races end up using square wheel and tire set ups (unless they have very high power levels) because of the control and ability to manipulate the car in certain ways are much higher when there is greater front end grip. It really comes down to everyone's different preferences with their own car and their driving styles.

Thanks for the insight Joe. What is the preferred square setup? 18x10 or 9.5?

I've driven multiple 1ms on track. Standard wheel/tire configuration, standard wheels with 275 rears, standard with 295 rears and 18x10s running 275s (or maybe it was 265s) all around. I was absolutely shocked by the difference the square setup made. The 1m has always felt a little bit twitchy to me at the limits and also hard to perfectly balance. It's a great car but not real comfortable sitting right at 9/10ths. With the square setup that totally changed. It became extremely predictable and progressive. It went from a car that I drove around the track and somewhat reacted to when things happened to a car that I could attack the next corner with. For me, it went from another street car that’s occasionally fun to take out on track to a car I can’t wait to get on track again.

Granted everyone’s driving style is different and opinions will vary. This is just mine

Thanks for the insight Joe. What is the preferred square setup? 18x10 or 9.5?

If your 1M is stock than we like to see 18x9.5" ET22 square with a 265/35/18 tire. If you have camber plates installed on your 1M than it is possible to do 18x10" ET25 with either 265/35/18 or 275/35/18 tires.

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Originally Posted by CarJunkie

Wow, that is some serious analysis there!

For 18x9.5 et35, would a wheel spacer be needed? It seems like the et27 would be the better fit if available.

18x9.5" ET35 is extremely close to the front strut on a stock 1M and can sometimes clear depending on the type of tire that is used. A 255/35/18 would definitely clear the front strut and a smaller running 265/35/18 tire like the Hankook V12 could possibly clear. If you are having rubbing issues than you could use a 5mm wheel spacer to clear the front strut. An 18x9.5" ET22 is a direct fitment for the front of a 1M with a 265/35/18 tire.

A square set up will significantly reduce understeer on an otherwise stock car and greatly attributes to a more neutral handling car. The ability to rotate and work the car through the corner also becomes much easier when you have the same amount of grip in the front as the rear, in a square set up. Almost all BMW owners at track days and club races end up using square wheel and tire set ups (unless they have very high power levels) because of the control and ability to manipulate the car in certain ways are much higher when there is greater front end grip. It really comes down to everyone's different preferences with their own car and their driving styles.

Yes, true on the reduction of understeer, but at the expense rear traction. 1M needs the widest wheel/tire possible under the rear fenders to control the hp and tq coming out of the turns. The purpose is to give you the highest possible corner exit speed by getting back into the throttle at the earliest point in the corner as possible.

A better solution to understeer is more camber and a balanced suspension set-up.

Yes, true on the reduction of understeer, but at the expense rear traction. 1M needs the widest wheel/tire possible under the rear fenders to control the hp and tq coming out of the turns. The purpose is to give you the highest possible corner exit speed by getting back into the throttle at the earliest point in the corner as possible.

A better solution to understeer is more camber and a balanced suspension set-up.

Considering a 17x10 square setup with 275/40 tires, with the option to move to a 10.5 rear if I feel the need to have more tire. Apparently the 17x10 and 10.5 will clear our stock brakes and most 355 brake kits. Seems like a no brainer to me given the money I would save on tires.

Considering a 17x10 square setup with 275/40 tires, with the option to move to a 10.5 rear if I feel the need to have more tire. Apparently the 17x10 and 10.5 will clear our stock brakes and most 355 brake kits. Seems like a no brainer to me given the money I would save on tires.

I'm running 275 on 9.5" square and so is M3adjuster. The square setup reduces the understeer that's associated with the stock tire setup.

Is your suspension stock? If yes, square is the way to go because the front camber adjustment range on the stock suspension isn't sufficient and you'll be eating up the outer edge of your front tires.

Mine are actually 18 x 10 ET 25 square.

Take off 275/35/18 grand am (hoosier/continental) tires are awesome. Also have used 265/35 hankook rs 3. Both work with no rubbing on stock car. I do also have camber plates but those were added after both tires were tried. I am very happy with square setup.